/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Parameterization/MeshRegionGraph.h
bool MergeSmallRegionsPass ( int32 SmallThreshold, [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< float(int32 SmallRgnIdx, int32 NbrRgnIdx)> RegionSimilarityFunc )